New evidence for a critical role of elastin in calcification of native heart valves: immunohistochemical and ultrastructural study with literature review.

AIMS: Calcific aortic stenosis is a progressive disease characterized by massive fibrosis andmineralization of the valve leaflets. The aim of this study was to determine whether the onset of native calcific aortic stenosis is associated primarily with matrix remodelling events, and particularly with elastin degradation. METHODS AND RESULTS: The immunohistochemical expression profile of matrix degradating enzymes and tenascin-C was investigated in both healthy and native calcified aortic valves. Collagen and elastic tissue were studied by light microscopy and electron microscopy. Immunophenotypic analysis of inflammatory cells was carried out by using monoclonal antibodies to macrophages, T and B lymphocytes. Immunoreactivity for tenascin-C and matrix metalloproteinase-12 (MMP-12) was associated with areas of dense mineralization, which were characterized by fibrosis, fragmentation and calcification of elastic fibres a positive reaction was also found around small islands of calcification. MMP-11 was not detected in the diseased valves. Osteopontin and osteonectin were also found at sites of mineralization. All calcified valves examined showed inflammatory cell infiltration. CONCLUSIONS: Our results demonstrate the direct involvement of MMP-12 in native aortic valve stenosis. MMP-mediated degradation of elastic fibres might contribute actively to valve mineralization by inducing calcium deposition onto fragmented elastin.

Surgical results of aortic valve replacement via partial upper sternotomy: comparison with median sternotomy.

BACKGROUND: the theoretical advantages of mini-invasive cardiac surgery are shorter hospitalisation, better surgical results and costs reduction. In November 1997 we started a non-coronary mini-invasive surgery program using a partial upper median sternotomy. This study has been conceived to retrospectively compare two groups of patients who underwent isolate aortic valve replacement using the conventional and the mini-invasive technique. MATERIAL AND METHODS: in Group A 100 patients (mean age 62+/-12 years; 58 male) underwent isolated aortic valve replacement through a partial upper median sternotomy. Group B was composed by the last 100 patients (mean age 63+/-8 years; 56 male) who underwent the same operation through a conventional median sternotomy. For both groups we recorded the ECC and ischaemic times, postoperative intubation time, total postoperative bleeding, intensive care unit length of stay and total hospitalisation time. Major and minor complications were reported. RESULTS: operating times, were significantly longer in Group A (p<0.001). Mechanical ventilation time, ICU and total hospital stay, and total postoperative bleeding showed no significant difference. Adjunctive statistical evidenced the absence of learning curve. Mortality and other complications failed to reveal any significant difference between the two groups. CONCLUSIONS: in our experience, partial upper median sternotomy does not increase surgical risks but failed to demonstrate clear advantages. Apart for an increase in operating times, the surgical results are similar to those of a conventional median sternotomy with only improvement in the aesthetical aspect. In our opinion, this supports the conviction that this approach can be proposed to selected patients, to obtain a better cosmethical result for the same given risk.